Jarisch-Herxheimer Reaction

The Jarisch-Herxheimer reaction is a temporary immune response that can occur after starting antibiotic treatment for certain spirochete infections, including syphilis, Lyme disease and relapsing fever. It is thought to result from the rapid release of toxins and inflammatory substances as large numbers of bacteria are killed off at once, producing fever, chills, muscle aches, headache and a brief worsening of the underlying disease skin or other symptoms within hours of the first antibiotic dose. The reaction is usually self-limited, resolving within a day, and is managed with supportive care such as antipyretics rather than stopping the antibiotic. It is named for the physicians Adolf Jarisch and Karl Herxheimer, who described it in patients being treated for syphilis.